Twenty-one magnet programs in the Houston Independent School District in Texas feature an enriched curriculum in science, math, and/or computers (science/math). Of these, 12 are elementary programs, 4 are middle school programs, and 5 are high school programs. In these programs, a total of 9,574 students were served during the 1990-91 school year: 6,372 elementary, 3,358 middle, and 1,834 high school students. Fifth grade students enrolled in the seven elementary Science/Math Add-On Programs did not score significantly higher than the comparison groups on the MAT6 science tests, and in only one program did students score significantly higher than their matched comparison group on the MAT6 math tests for the 1988-89 or 1990-91 school years. Fifth grade students enrolled in five elementary School-Within-A-School Programs (SWAS) scored significantly higher than the comparison groups on the MAT6 science tests during the 1988-89 or 1990-91 school years after being enrolled 3 to 5 years, respectively, in the enrichment programs. In two of the SWAS programs, students scored significantly higher than the comparison groups on the total math tests. Eighth grade students enrolled in the three middle school SWAS programs that were evaluated scored significantly higher than the comparison group on the MAT6 science tests during the 1988-89 or 1990-91 school years. In two of the SWAS programs, students scored significantly higher than the comparison groups on the total math tests. (Author/MDH)